/*
 * 
 * Original author: alpha_lam
 * Creation date: ?
 *
 * Source: $HeadURL$
 * Last changed: $LastChangedDate$
 * 
 * 
 * the unrar licence applies to all junrar source and binary distributions 
 * you are not allowed to use this source to re-create the RAR compression algorithm
 *
 * Here some html entities which can be used for escaping javadoc tags:
 * "&":  "&#038;" or "&amp;"
 * "<":  "&#060;" or "&lt;"
 * ">":  "&#062;" or "&gt;"
 * "@":  "&#064;" 
 */
package de.innosystec.unrar.rarfile;

public class FileNameDecoder {
	public static int getChar(byte[] name, int pos) {
		return name[pos] & 0xff;
	}

	public static String decode(byte[] name, int encPos) {
		int decPos = 0;
		int flags = 0;
		int flagBits = 0;

		int low = 0;
		int high = 0;
		int highByte = getChar(name, encPos++);
		StringBuffer buf = new StringBuffer();
		while (encPos < name.length) {
			if (flagBits == 0) {
				flags = getChar(name, encPos++);
				flagBits = 8;
			}
			switch (flags >> 6) {
				case 0:
					buf.append((char) (getChar(name, encPos++)));
					++decPos;
					break;
				case 1:
					buf.append((char) (getChar(name, encPos++) + (highByte << 8)));
					++decPos;
					break;
				case 2:
					low = getChar(name, encPos);
					high = getChar(name, encPos + 1);
					buf.append((char) ((high << 8) + low));
					++decPos;
					encPos += 2;
					break;
				case 3:
					int length = getChar(name, encPos++);
					if ((length & 0x80) != 0) {
						int correction = getChar(name, encPos++);
						for (length = (length & 0x7f) + 2; length > 0 && decPos < name.length; length--, decPos++) {
							low = (getChar(name, decPos) + correction) & 0xff;
							buf.append((char) ((highByte << 8) + low));
						}
					} else {
						for (length += 2; length > 0 && decPos < name.length; length--, decPos++) {
							buf.append((char) (getChar(name, decPos)));
						}
					}
					break;
			}
			flags = (flags << 2) & 0xff;
			flagBits -= 2;
		}
		return buf.toString();
	}
}
